Robot Arms Embrace Space Station Cargo Duties

NASA's Mission Control team took over cargo operations aboard the International Space Station this week, commanding Canadian furnished robot arms to reach into the recently berthed SpaceX Dragon resupply capsule to extract a pair of external experiments -- the agency's own HDEF commercial high definition external video camera assessment and the OPALS laser communications evaluation.

Ground command of the 58-foot-long Canadarm2 and two armed 11-foot-long Dextre has become near routine in the post-assembly phase of the six person ISS in order to keep crew time focused on internal research, explained NASA's Troy McCracken, who serves as MCC lead for the robotic activities that began Wednesday and were expected to take three days or more.

Astronaut control of the robot arms is reserved primarily for capturing the U.S. commercial Dragon and Cygnus resupply capsules and Japan's H-2 Transfer Vehicle as well as moving crew members around during spacewalks. The division of duties also allows station crews to focus on research activities as they train before flight rather than learn some of the more complex operating procedures required for Dextre.

Both HDEF and OPALS arrived April 20 aboard the latest Dragon mission, stowed inside the unpressurized "trunk," a compartment at the back of the capsule reserved for hardware that will not come inside the ISS.

Canadarm2 and Dextre can be re-anchored around the station by the MCC team, or fastened to the Mobile Transporter, a rail car that rides along the station's 356-foot-long solar power truss. For HDEF and OPALS unstowing, McCracken and his controllers placed Dextre in the grasp of the Canadarm2 to extract and install HDEF on an Earth-facing attach point on the European Space Agency's Columbus laboratory.

HDEF was switched on quickly and was beaming back imagery Thursday as efforts to transfer OPALS to the Express Logistics Carrier 1 on the station's port side truss got under way.

New HDEF video package beams down crisp views of Earth 260 miles below, with Dragon, Canadarm2 and Dextre in the foreground. Image Credit: NASA TV

OPALS, developed at the Jet Propulsion Laboratory, will evaluate the use of laser transmissions to improve space communications.